The mirror glass on all my Omegas demist correctly and the 'silver' on the back are presumably all good as there is no visible discolouring of the glass itself. Going off the performance of my mirror glasses which are all well over 15 years old, I have no reason to doubt the performance of any secondhand mirror glasses as long as they are visibly in good order.It's a bit of a sweeping statement to say that all secondhand mirror glasses will have weak demisters.......

The mirror glass on all my Omegas demist correctly and the 'silver' on the back are presumably all good as there is no visible discolouring of the glass itself. Going off the performance of my mirror glasses which are all well over 15 years old, I have no reason to doubt the performance of any secondhand mirror glasses as long as they are visibly in good order.It's a bit of a sweeping statement to say that all secondhand mirror glasses will have weak demisters.......

The demisters do degrade. Compare an old one to a new one, and you will see.